BOSTON
— Nov. 24 - Poor Dickens! His opening words in "A Tale of Two Cities" are likely to be commandeered by innumerable writers trying to sum up the 20th century.

For wasn't this, indeed, the best of centuries and the worst of centuries?

It was clearly both. But, arguably, the best outweighed the worst. Humanity did progress apace, harvesting the myriad fruits of the knowledge explosion. It also tried, fitfully, to devise institutions to prevent future germination of the dark fruits that blighted the century: genocides, world wars, the Great Depression, environmental recklessness.

During the 20th's triumphant and tragic course, the human race not only learned to fly (not just balloon) above the surface of the planet, but left Earth entirely for mankind's epic first ventures into the universe. In little more than half a century, flight speed rocketed from 6.8 miles per hour at Kitty Hawk to 17,500 m.p.h. at Cape Canaveral.

Humans literally took off for the first time in history. And the liftoff acceleration was mirrored in many earthbound fields. We sped toward a global civilization - linked by a floodtide of inventions, experiments in peacekeeping and global rule-making,

surging trade, and rapid communications.

Life was quantifiably better for a larger portion of the planet's people than ever.

By mid-century, French phi-lospher Raymond Aron glimpsed what he called "the dawn of universal history." That meant all of mankind at last starting to write on - and read off - the same page.

By century's end, the dawn of universal history had edged toward noon. (But not without casting heavy shadows.) The human race - with all its distinct ethnic tongues, foods, costumes, customs, and prejudices - moved perceptibly closer to one address. Call it www.earth.

Jeans, Zines, cuisines

Humanity became webbed together in ways that would have startled that cultural export-import maven, Marco Polo. The main link was joint experiences - of World Cups; sitcoms dubbed in scores of languages; citizens born to those tongues but learning the worldtongue, biz-English; living room wars; jeans, zines, cuisines; ethnopop fusion; blockbuster traveling art shows; chain-linked economic booms and busts; Japanese cars built in Europe; German carmakers following German rocket scientists to Alabama; Mona Lisa printed on Asian handkerchiefs; and Beethoven's Ninth everywhere.

Much of this could be parodied, or even sneered at. But who's to argue that hearing the Ode to Joy for the first time in Beijing is any less moving a discovery than hearing koto music for the first time in Omaha. Nobody criticizes the 19th century equivalent: French Impressionists discovering Chinese brush painting, or Puccini galvanized by Asian music.

Free of gravity, little else

A more pertinent question at century's end is this: were humans freer than at the start?

Of gravity, yes.

Of terra incognita, yes.

Of colonialism, mostly.

Of racism, somewhat.

Of ideological blinders, the jury is out. Many ideologies were discredited and discarded, but new ones were fashioned. Those ranged from primitive cult of personality Kim-ism in North Korea to various fundamentalisms that rejected the modern world, to the lethal lure of Japan's Om cult, to the PC litany: Don't think; we're in charge of that.

And what about other historic ballast holding men and women down - the societal equivalent of gravity: War, cruelty, hunger, addiction, hubris, apathy, greed? Steps forward. Steps backward.

Martin Luther King's visionary cry "Free at last" saluted not astronauts but the human spirit and universal brother/sisterhood. On that score, freer at last - not free - is clearly a more realistic appraisal of this jampacked century.

The century and millennium end with major net progress. But it's a matter of progress in progress rather than progress fully accomplished.

Netting out progress

Decolonization left us nearly free of imposed empires for the first time in well over two millennia, but not yet free of other forms of despotism. It helped erode racism by getting rid of white rule over nonwhite subjects. But it still took further battles, like the epic struggle against apartheid in South Africa, to push brotherhood among humans beyond gospel, slogan, or UN declaration.

The once (and future) Asian economic miracle effectively undermined another pervasive racism. But the goal of color/ethnic blindness still lay uphill, as anti-Muslim stereotypes replaced earlier forms of antisemitism. Europe and America wrestled with immigration pressures that fueled new and old prejudices.

Nevertheless, democracy spread. So did women's rights, literacy, high-yield farming, family planning, and the information explosion. But so, also, did cutting of rainforests, spreading of deserts, drying of the Aral Sea and other waterways, inching up of ocean levels, and inefficient burning of fossil fuels. (The last phenomenon worriedly watched, as researchers sought evidence of whether it was the main cause of climate and sea level change.)

Urge to merge ... nations

Nations experimented with new institutions for economic and political cooperation. Western Europe amalgamated in the wake of its second lethal world war. The European Union, a looser, less homogenized version of a united states, invited its east European siblings to join after the long cold war against the last big empire - Stalin's - ended.

Other, looser conglomerating took place even as empires faded and alliances shifted. Regional trade groups in North America, the big states of South America, and Pacific Asia joined the European trade area as zones of reduced commercial barriers. Some economists feared zone trade wars between the Western Hemisphere, Europe, and Asia. But cooperation appeared to be gaining ground.

The big wars, big depression, and genocidal outbreaks of the century spawned a series of earnest but mostly toothless world and regional political bodies, plus courts, trade referees, peacekeeping forces, election monitors, and ordinary traffic light-style global machinery.

Cranking world machinery

The post-World War I League of Nations didn't last, so nations went back to the drawing board to create the United Nations, revive a sometimes useful but scarcely visible World Court, vote a score of peacekeeping experiments, and set up ad hoc war crimes tribunals. Peacekeeping worked when the warring parties were exhausted or big powers twisted their arms. But preventing wars before they started was still an imperfect art.

Several rounds of reducing trade barriers led to a permanent World Trade Organization to provide a home for future bargaining and a referee for disputes. The World Bank and International Monetary Fund, plus regional development banks attempted to perform globally some of the business cycle taming and development funding that national banks did within countries.

Much of that machinery was born out of lessons from the Great Depression. That global tragedy, sandwiched between world wars, hammered home the costs of tit-for-tat trade protectionism, rigid central banks, rampant deflation, and the panicky tightening of credit. Franklin Roosevelt described the overall cause in his famous "the only thing we have to fear is fear itself" speech in 1933.

The post-World War II spate of institution-building did much to make the world more orderly. (Test yourself on this selection of acronyms: UN, IMF, UNHCR, UNICEF, NATO, OAS, CIS, OAU, ASEAN, OECD, FAO, IAEA, UPU, WHO, EU, NAFTA, OPEC.)* But it stopped short of developing an international antitrust system or other machinery to help keep the playing field level for competing global businesses and workers.

Longevity stretched for homo sapiens and rebounded for some endangered species, but not for others. Trade expanded hugely, spreading prosperity - and rising expectations. Invention vastly changed the whole surface of daily life (but not life's quality or meaning) - from washing machines to horseless carriages, to frozen peas, movies, TV in every home or village, cell phones, and the world wide webbing of nearly everything.

All represented advances at home and work. One result: the work week shortened, home chores became more efficient, and the concept of servants at home and assembly line drones in the workplace shrank in the developed world and came under pressure in parts of the emerging world.

But then trade competition from developing Asia and Latin America sent some trends into reverse. The trickle of women in the workplace early in the century became a torrent. Some servant-surrogates reappeared as au pairs, nannies, and maintenance services for upper end households, and day care centers for lower end.

Once again, the net effect was progress. Saturday work shrank. Leisure increased. But the net advance came without the triumphalist belief in capital-P progress proclaimed so confidently at 19th century's end.

There was good reason for such lack of crowing. The 20th century's more modest claims of progress were plumb-weighted by the knowledge that each generation had to learn lessons about the misuse of innovations and the awful toll such misuse could cause. It was, in Biblical terms, a reminder of eating of the fruit of the tree of knowledge of good and evil. Gaining the benefits of the good fruit required an active denial of any repetition of the evil fruit.

Tragic 'coercive utopias'

As earlier noted, the 20th century provided a grim lesson book recording the unbearable costs of what Zbigniew Brzezinski caustically dubbed "coercive utopias." Those anti-utopias took George Orwell's "1984" universal dictatorship a chilling order of magnitude further - into concentration camps, world wars, brainwashing, killing fields, cultural revolutions, ethnic cleansing, and multifarious Big Brotherisms that mocked real brotherhood.

By century's end these pointless exercises in mass mind control and end-justifies-whatever-means propaganda had killed between 167 million and 175 million individual human beings. Looking back, it's hard for today's generation to believe that so many humans believed in the cruel ideological certainties force-fed by Hitler, Stalin, Mao, Pol Pot, and a slew of lesser despotic pied pipers.

One lesson: teach children (and adults) to see through propaganda. That means parsing the half-truths of demagogic politicians, irresponsible ad agencies, and script-sensationalizers, as well as the outright lies of mind-capturing despots.

A second lesson: keep the dark byproducts of scientific innovation out of the hands of malign dictators.

Threat of NBC weapons

Look no further than the search for NBC (nuclear, biological, chemical) weapons in Iraq for a condensed version of this lesson.

Throughout the 20th century, discoveries about the nature of the physical macrocosm and microcosm radically changed our understanding of physics, biology, and chemistry.

But - despite the intellectual and practical benefits flowing from the theoretical leaps of Einstein, Bohr, Watson, Crick, and the many fathers of the computer, artificial intelligence, rocketry, and chemical theory - there was a dark underside to each.

The new physics promised limitless power generation and controlled-fission canal blasting . But it also wrought Hiroshima and disputes over disposal of hazardous waste.

The new biology promised designer animals and food plants, with built-in herbicides, insecticides, and frost and drought resistance. It promised genetic Maginot lines against disease. But it also brought controversy over the ethics of cloning and risks to ecological balance in nature.

"Better living through chemistry" was abundantly evident in shelter, clothes, transport, farms, even golf clubs and tennis racquets. But chlorofluorocarbons threatened the atmosphere and other chlorine compounds and assorted agricultural chemicals still cause problems for the planet's surface and its wealth of useful organisms.

'Mein Kampf' to docudrama

An analogous downside exists even for the glamorous innovations that made possible the information and entertainment revolutions of the century: radio, TV, recordings, and the internet.

As earlier noted, most of these advances knit mankind together through the broadcast of common experiences. But, just as Socrates complained that the invention of writing would damage memory (oral history and epic tales), so each new advance in communication held risks as well as extraordinary benefits. Movable type put books in the hands of the ordinary man and woman, made possible the enlightenment and the industrial revolution. But it also allowed the spread of "Mein Kampf" and degrading pornography.

Each of the 20th century communication breakthroughs provided widespread benefits - and analogous downsides. The most recent example is the internet, where misinformation (even disinformation) and porn flow seamlessly alongside rivers of useful information.

Then there's that marvelous invention, TV, where infotainment, political attack ads, and docudrama threaten to outflank and outpull legitimate news, history, and entertainment.

None of this downside has the killing power of NBC weapons. But it endangers the educated citizenry needed to run the democracies that have spread around the globe.

The French say high school graduates know everything, but nothing else. That ironic description could easily fit today's media addicts, pelted with both facts and non-facts, events and pseudo-events, but lacking perspective to sort one from the other.

Lessons for 21st century

Looking over the high-velocity changes in the 20th century, it's clear that huge amounts of useful progress occurred. As already argued, that progress outweighed the shameful negatives. Lessons were learned, and institutions created, to try to prevent a recurrence of the negatives.

Moving through a continuum (not across a bridge) to the 21st century, the human race faces the question of how to keep the lessons of the 20th century's tragedies fresh in memory as it builds on the cornucopia of beneficial innovations. Perhaps the biggest challenge will come in a field growing at the end of the 20th. That's the famous mouth-twister, "sustainable development (SD)."

In simplest terms SD means researching new industrial processes and individual daily routines that will allow both (1) better living standards for billions of deprived people and (2) protecting the planetary environment. That involves creating economic growth worldwide with industrial processes that create zero or near-zero net pollution.

That's the big new struggle. To work, it will need to grow alongside:

* Keeping the trend toward lower birth rates on track.

* Maintaining vigilant control of the spread of nuclear, biological, and chemical weapons.

* Realistic strengthening of the world peacekeeping system.

* Continued lowering of trade barriers - allowing industry to thrive worldwide and prevent mass migrations of the unemployed and poor.

* A regularized war crimes prosecution system to ward off atrocities that lead to revenge warfare and the desire to acquire NBC weapons.

* Realistic, family-reinforced anti-drug education that is tough on the siren-song of propagandists and pushers.

* Carefully controlled research on designer food crops that will shrink pollution from herbicides, insecticides, and fertilizer runoff.

* Encouraged spread of democracy through vote-monitoring where needed, and through education in demagoguery detection.

None of it an easy job, as one century's inhabitants hand the baton to those who will inhabit the next. Not easy. But doable, given enough vision, spiritual confidence, and determination.